Tobacco composition

ABSTRACT

A SMOKING PREPARTION COMPRISING TOBACCO AND A ZEOLITE ATERIAL WHICH EFFECTS A DECREASE IN THE AMOUNTS OF POLYCYCLIC AROMATIC COMPOUNDS PRODUCED FROM THE PYROLYTIC REACTIONS OF TOBACCO, THE ZEOLIT MATERIAL BEING OF THE Y-TYPE STRUCTURE, PREFERABLY AT LEAST PARTIALLY EXCHANGED WITH ZINC IONS OR CONTAINING METALLIC PALLADIUM, OR AT LEAST PARTIALLY EXHANGED WITH ZINC IONS AND CONTAINING METALLIC PALLADIUM, OR IS PARTIALLY POLYVALENT ZINC CATION EXCHANGED AND PARTIALLY DECATIONIZED AND CONTAINS METALLIC PALLADIUM.

United States Patent 3,572,348 TOBACCO COMPOSITION Vello Norman, Chapel Hill, and Thomas Blair William, Andrew George Kallianos, and James Davis Mold, Durham, N.C., assignors to Liggett & Myers Incorporated, New York, N .Y. No Drawing. Filed Aug. 1, 1968, Ser. No. 749,324 Int. Cl. A24b /02 US. Cl. 131-17 12 Claims ABSTRACT OF THE DISCLOSURE A smoking preparation comprising tobacco and a zeolite material which effects a decrease in the amounts of polycyclic aromatic compounds produced from the pyrolytic reactions of tobacco, the zeolite material being of the Y-type structure, preferably at least partially exchanged with zinc ions or containing metallic palladium, or at least partially exchanged with zinc ions and containing metallic palladium, or is partially polyvalent zinc cation exchanged and partially decationized and contains metallic palladium.

DISCLOSURE OF THE INVENTION The invention relates to a tobacco preparation containing crystalline aluminum silicate zeolites and more particularly to such preparations containing specific zeolites as described.

Observations of the mechanism of combustion in tobacco preparations, such as cigarettes, indicate that the smoke components responsible for biological activity are formed in the pyrolysis zone of the cigarette cone. It has been suggested that the formation of such smoke components involves free radicals as intermediates. Based upon this concept, it had been proposed that zeolite materials having free radical promoting catalytic activity be used to control or influence free radical formation in the pyrolysis zone and thereby cause alterations in the structure of the pyrolysis products formed in expectation of a reduction in biological activity. An alternative suggested mechanism involves the participation of ionic species in the reformation process of smoke components. It has also been proposed that zeolite materials which are known to promote carbonium ion activity be used in an attempt to influence smoke composition.

Tobacco preparations containing zeolitic materials are known. For example US. Pat. No. 3,292,636 discloses tobacco preparations in combination with crystalline zeo lite molecular sieves such as the L, X, Y or synthetic mordenite types, or naturally occurring faujasite materials, which sieves may contain any metal having a vapor pressure below 1 atmosphere at 1,000 C. and possessing catalytic activity for organic conversion. Such materials are said to result in tobacco preparation wherein vaporized and at least partially oxidized, but unidentified irritant materials, are rendered less irritable to the smoker while the tobacco preparation is being consumed.

It has now been found that the mere possession of a certain type of activity of these catalytic materials does not sufiice to decrease the biological activity of smoke and that a significant number of materials disclosed in US. Pat. No. 3,292,636 are not only ineffective for the purpose of decreasing the biological activity of smoke fractions produced on combustion of tobacco preparations and in decreasing the yield of certain polycyclic aromatic hydrocarbons which are produced from tobacco in pyrolysis reactions but even significantly increase the yield of such products. It has been further discovered that particular zeolite materials preferably containing particu- Patented Mar. 23, 1971 lar metals are unique in their ability to significantly decrease the amounts of certain polycyclic aromatic hydrocarbons which are normally produced from tobacco upon pyrolysis. The present invention comprises application of this surprising discovery to cigarettes, cigars and other smoking tobacco preparations.

Accordingly, it is an object of this invention to provide a smoking tobacco preparation which on burning substantially reduces the level of polycyclic aromatic compounds in smoke.

Other objects will be apparent from the disclosure and appended claims.

According to this invention, a novel smoking preparation is provided which comprises tobacco, and a zeolite composition consisting essentially of a Y-type crystalline zeolite molecular sieve having pores sufficiently large to receive benzene and preferably at least partially exchanged with zinc or containing catalytically active palladium or at least partially exchanged with zinc and containing metallic palladium. In one preferred embodiment the type Y zeolite is partially or completely zinc exchanged. In another preferred embodiment the type Y zeolite is partially or completely zinc exchanged and contains added metallic palladium. In a third preferred embodiment the type Y zeolite is partially polyvalent cation exchanged and partially decationized and contains metallic palladium. The metal is incorporated in finely divided form in the inner adsorption region of the molecular sieve in quantity sufiicient to constitute between about 0.05% and 15% by weight of the catalyst composition. At least 0.05 weight percent metal is required to obtain some catalytic conversion of the vaporized organics and more than 15% metal does not appreciably improve the etfectiveness of this conversion. A range of from about 0.1% to about 10% by weight catalytically active elemental metal is a preferred balance of these characteristics. The catalytic composition can be added to tobacco by dispersing it uniformly as particles smaller than about mesh or it can be incorporated as an ingredient in the manufacture of reconstituted tobacco sheet. The catalyst composition comprises at least 0.5% by weight and up to about 50% and greater by weight of the smoking preparation. At least 0.5 weight percent catalyst composition is needed to effect some degree of adsorption and catalytic conversion of the vaporized organics. Quantities in excess of about 50% do not effect a significant increase in reduction in the yield of polycyclic aromatic hydrocarbons produced in pyrolysis reactions from the tobacco mixture. A range of about from 1% to about 35% by weight catalyst composition in the smoking tobacco preparation represents a preferred balance of these requirements. Proportions significantly greater than about 40% are commercially impractical.

The zeolite composition consists essentially of the highly selective molecular sieve and preferably a catalytically active metal contained in the finely divided form in the inner adsorption region of the molecular sieve. The catalyst composition is uniformly dispersed in the tobacco so that it is present in the zones of burning, preheating and the region of substantially ambient temperature.

As to the particular crystalline zeolite molecular sieves, they may be described as being of the Y-type, consisting of an open three-dimensional framework of $0., and A10 tetrahedra which are cross-linked by the sharing of oxygen atoms, so that the ratio of oxygen atoms to the total of the aluminum and silicon atoms is equal to two, or O/(Al+Si)=2. The negative electro-valence of tetrahedra containing aluminum is balanced by the inclusion within the aluminum silicate framework of cations, for example, alkali metal, and alkaline earth metal ions such as sodium, potassium, calcium, and magnesium ions. One cation may be exchanged for another by ion exchange techniques. The void spaces in the framework are occupied by water molecules.

Type-Y zeolite may be represented by the formula:

wherein x is a value greater than 3 up to about 6 and y may be a value of to about 9. Zeolite Y has pores of about 10-13 angstroms size, and is described in US. Pat. No. 3,130,007.

The Y-type zeolites and processes for preparation thereof are well known in the art, including processes for preparing the zeolites with the metals referred to above.

For use in the present invention, the molecular sieve must have pores sufilciently large to receive benzene. This is because the organic vapors formed during the smoking of tobacco preparations vary in critical dimension from relatively small to as large as the benzene molecule. If a relatively small pore molecular sieve were employed, the large molecules of organic vapors would be blocked by the pores and could not pass into the inner adsorption region of the molecular sieve. Since the surface area of this inner region is about one hundred times the external surface area the molecular sieve would be largely ineffective for both adsorption and contact between organic vapors and the catalytically active metal.

The catalyst composition should be well dispersed through the tobacco so that it will be uniformly effective during the entire smoking of the preparation. For this reason, it is employed as a fine powder of particle size smaller than about 100 mesh. Also, the fine powder form eliminates the need for a tobacco-catalyst composition binder which would be needed if the latter were introduced as relatively large particles. The powder may be added to the tobacco at any of several points in the tobacco pyrolytic reactions with tobacco. These zeolitic materials are all well known in the art in the described terminology and are commercially available. In each of the test runs described, finely-ground cigarette tobacco was combined with the finely-powdered zeolite described and the well blended mixture was sifted into a 3 ft. long Vycor tube of 1 inch diameter which was maintained at 800 C. while nitrogen gas flowed through it at the rate of 17.5 cc. per second. The pyrolysis products were collected in liquid air-cooled traps and the pyrene content of the condensate was determined. Polycyclic aromatic hydrocarbons, of which pyrene is a representative member, are produced in much higher concentrations under these pyrolysis conditions than is the case for tobacco smoked in the form of cigarettes. This is due to the moreefficient pyrolysis which can be achieved under controlled conditions. The comparison of the eifectiveness of the zeolite additives in decreasing the yield of polycyclic aromatic hydrocarbons produced on pyrolysis of tobacco is given in Table I.

It is noted that the yield of polycyclic aromatic hydrocarbons, as exemplified by pyrene, actually increased in most cases for the samples pyrolysed with added X-type zeolite materials, whereas, a decrease in yield of pyrene was observed relative to the control for the samples pyrolysed with Y-type zeolite materials. This effect was most pronounced for the Y-type zeolites which were zinc exchanged or contained added metallic palladium at higher levels of the added zeolites.

Samples pyrolysed with either partially polyvalent cation exchanged and partially decationized Y-type zeolites, Y-type zeolite (sodium form), or A-type zinc exchanged zeolite showed relatively less effect on the yield of pyrene, but yet a measurable reduction when comprocessing operation. For instance, it may be dusted into pared to the various X-type sieves.

TABLE I Pyrene Yields g/g. tobacco) in 800 C. Pyrolysates Pyrene Pyrene Percent Percent Type of zeolite added zeolite in Percent zeolite in Percent to tobacco tobacco pg. of control tobacco ug. of control Control (no zeolite) 0 235 X-Ag 5 268 .X-Cu 5 258 X-Na+ 5 267 Y rare earth exchanged,

dccatlonized 5 222 Y rare earth exchanged,

decationized plus Pd 5 217 92 62 26 Y-Zn++ exchanged 5 194 82 50 106 49 A-Zn++ exchanged 5 219 93 50 207 88 Y-Na+ 10 223 95 50 142 the tobacco leaves entering the shredding machine or it may be added after the tobacco leaves have been shredded and clarified of stem pieces and other debris. Alternatively, the catalyst composition may be introduced along with other additives, such as humectant or flavoring which are also added in a manner to assure uniform dispersion in the mixture. It is especially suitable to incorporate the catalyst composition by commingling with powdered tobacco and stem or other fibers prior to reforming into a reconstituted tobacco sheet.

The smoking preparation may be further processed and formed into any desired shape, e.g., cigars and cigarettes, in a manner well-known to those skilled in the tobacco art.

The invention will be more clearly understood from the following example which is provided by Way of illusstration and not limitation and in which the proportions are in parts by weight unless otherwise stated.

EXAMPLE 1 In this example the particular Y-type zeolites useful for this invention, and various other zeolite materials are compared with respect to their efiect on the yields of certain polycyclic aromatic hydrocarbons obtained in It will be understood that it is intended to cover all changes and modifications of the descriptive examples of the invention wherein chosen for the purpose of illustration which does not constitute departures from the spirit and scope of the invention. It is further understood that the Abstract of Disclosure is included in this specification solely for purposes of Rule 72(b) of the Rules of Practice of the US. Patent Ofiic'e.

We claim:

1. A smoking preparation comprising:

(a) tobacco; and,

(b) Y type zeolite material at least partially zinc exchanged which decreases the yield of polycyclic aromatic compounds arising from pyrolytic reactions cationized and contains metallic palladium in finely divided form in the inner adsorptive region of said zeolite.

5. The preparation of claim 2 wherein the palladium contained in said zeolite is in finely divided form in the inner adsorptive region of said zeolite.

6. The preparation of claim 1 wherein the proportion of said zeolite is at least about 0.5% by weight of said preparation.

7. The preparation of claim 1 wherein the proportion of said zeolite containing metals is in the range of between about 0.5% and 50% by Weight of said preparation.

8. The preparation of claim 2 wherein the proportion of said palladium contained in said zeolite is in the range of between about 0.05% and 15% by weight of said zeolite.

9. The preparation of claim 1 wherein said zeolite containing said at least partially exchanged zinc is uniformly dispersed in said tobacco as particles smaller than about 100 mesh.

References Cited UNITED STATES PATENTS 3,292,636 12/1966 Mays l31--17 MELVIN D. REIN, Primary Examiner US. Cl. X.R. 131-262 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,57 ,3 Dated Patented March 23, 1

Inventor(s) Vello Norman; Thomas Blair William; Andrew Georg Kallianos; and James Davis Mold It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 7, Line 2 Change "metals" to "palladium."

Signed and sealed this 23rd day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Pateni 

